A method for preparing a polarizing film in which a dichroic material is adsorbed and oriented on a PVA (poly(vinyl alcohol)) layer is known. A typical application in which a polarizing film is used is a display device such as a liquid crystal display (LCD). For example, a PVA-based polarizing film having a thickness of about 60 μm to 80 μm or so is usually attached to both sides of a liquid crystal panel of a liquid crystal display.
The PVA resin is hydrophilic, and thus the polarizing film is sensitive to a change in temperature or humidity, is easy to elongate and contract, and easily causes defects such as so-called curls. Therefore, in order to inhibit the elongation and contraction and reduce the influence on temperature and humidity, usually, a protective film is attached to both sides of the PVA-based polarizing film. However, if the polarizing film is too thick, it is not easy to inhibit the elongation and contraction, and when the polarizing film is adhered to a liquid crystal panel or the like, stress is generated, thereby causing spots or the like on the screen. In addition, recently, while the demand for thin-type devices or low energy-consuming devices increases, the demand for thinner polarizing films is also increasing.
For example, Patent Document 1 and the like disclose a process for producing a thin polarizing film.